Self-leveling lifter



B. E. STENTZ SELF-LEVELING LIFTER July 8, 1969 Sheet Filed Nov.-. 5, 1967 INVENTORI BLAIR .E. STENTZ' zQgy-k a W B. EzSTENTZ 3,454,319

SELF-LEVELING LIFTER.

July 8, 1969 Sheet of 4 I INVENTOR. BLAIR E 5 TENTZ.

Filed Nov. 3, 1967 July 8, 1969 5. E. STENTZ 3,454,319

SELF-LEVELING LIFTER Filed Nov. 3, 1967 v Sheet 4 of 4 lNVENTCR: BLAIR E. ETENTZ.

BY/Qygggw ATTYS.

United States Patent Int. Cl. B65g 1/16 US. Cl. 312-71 12 Claims ABSTRACT OF THE DISCLOSURE A self-leveling lifter for storing stacked articles such as dishes or trays. The articles are stacked on a platform which lowers or raises as the stack increases or decreases, to keep the top of the stack at a predetermined elevation. Two oppositely wound spiral springs are attached at one end to a freely rotating axle which is mounted on the bottom of the platform. A reel is placed over and attached to the free end of each spring. Two tapes are wound on each reel. Each tape is directed over a pulley located at each corner of the platform and the end of each tape is attached adjacent the top of the lifter frame. As the platform is pushed down, the tapes unwind causing the two reels to turn in opposite directions. As the two springs turn against each other the spring forces are increased, urging the platform upwardly. The upward forces balance the increased load resulting from the addition of stacked articles maintaining the top of the stack at the predetermined elevation. In another embodiment of the selfleveling lifter, a single spiral spring is connected between the two reels.

Background of the invention Many attempts have been made in the past to provide a satisfactory storing and dispensing apparatus for the handling of trays, dishes or similar articles of uniform Weight which are capable of being stacked. This type of apparatus is used in, for example, food handling operations in restaurants and hospitals.

Many of the prior art devices were suitable for the use intended when they were built for one article of a particular size and weight. However, most of the prior art devices could not easily be adjusted to accommodate stacked articles of a unit weight or a size different than the design weight or size. Adjustment of the prior art devices often required a separate spring or set of springs for each article of a different size and unit weight.

Summary of the invention The present invention solves the major problems of the prior art by providing a self-leveling lifter for storing and dispensing stacked articles which is easily adjusted to accommodate nonsymmetrical articles having a unit weight differing from the design weight.

The self-leveling lifter, according to the present invention, includes a support having a hole in its top for inserting stacked articles. The stacked articles rest on a platform which is mounted on guides below the hole. Two oppositely wound spiral springs are attached to a freely rotating axle, which is mounted on the bottom of the platform. Two reels are mounted coaxially with the axle and each reel is attached to one end of a spring. Two tapes are wound on each reel in a coil direction similar to the coil direction of its associated spring. Each tape is directed over a pulley at each corner of the platform such that the two tapes from one reel go to diagonal corners. The tapes are attached adjacent the top of the support. As the platform is pushed down, the tapes unwind, causing the two reels to rotate in opposite directions and the two springs to turn against each other. The platform will remain level even when the force pushing it down is not at its center. The spiral springs are adjusted so that the top one of the stacked articles will always be near the top of the support irrespective of how many articles are in the stack. In a second embodiment, a single spiral spring replaces the two spiral springs and the freely rotating axle.

It is a primary object of the present invention to provide an improved self-leveling lifter for storing and dispensing stacked articles.

Another object of the present invention is to provide a self-leveling lifter suitable for use when the load of stacked articles is not located at the center of the platform.

Still another object of the present invention is to provide a self-leveling lifter for storing stacked articles which is easily adjusted to operate with articles of a size and unit weight different than the design size and unit weight.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred form of the invention, reference being made to the accompanying drawings.

Brief description of the drawings FIG. 1 is a plan view of a self-leveling dish lifter embodying the features of the instant invention;

FIG. 2 is a side elevational view of a self-leveling dish lifter embodying the features of the instant invention, partially in section and showing the carrier platform in two different loaded positions in broken lines;

FIG. 3 is a fragmentary, vertical cross-sectional View of a guide post taken along line 11 of FIG. 1;

FIG. 4 is a fragmentary, horizontal cross-sectional view of the guide post taken along line 44 of FIG. 3;

FIG. 5 is an enlarged vertical cross-sectional view of the carrier platform taken along line 55 of FIG. 1;

FIG. 6 is an enlarged horizontal cross-sectional view taken along line 66 of FIG. 2 and showing the bottom of the carrier platform;

FIG. 7 is a partially sectioned, exploded view showing the axle in detail;

FIG. 8 is an enlarged, fragmentary cross-sectional view taken along line 88 of FIG. 5 showing the bolt arrangement for holding the tapes to the lower reel;

FIG. 9 is a cross-sectional view of the carrier platform taken along line 99 of FIG. 5; and

FIG. 10 is an enlarged, vertical cross-sectional view similar to FIG. 5, but showing an embodiment of the carrier platform using a single spiral spring.

Description of the preferred embodiments A self-leveling lifter for storing and dispensing stacked articles according to the present invention is generally indicated in FIGS. 1 and 2 by the reference number 10. The self-leveling lifter 10 includes a housing 11 and a carrier assembly 12 which is mounted on four guides 13. The guides 13 are mounted between a collar 14 and a base plate 17 at the bottom of the housing 11.

The collar 14 fits over a hole 15 cut into the top of housing 11 and is held in place by screws 16. The collar 14 has a hole 18 cut in its center for receiving stacked articles 19, which are stored in and dispensed from the self-leveling lifter 10. Guide posts 20, which are mounted on collar 14 by screws 21, keep the articles 19 that extend above the collar 14 stacked and also guide the stacked articles 19 into the hole 18. The uppermost one of the stacked articles 19 is located at a predetermined vertical elevation, which in the present embodiment is a few inches above the surface of the collar 14.

Referring to FIGS. 3 and 4, a hook 22 in the upper end of guide 13 is anchored in a hole 25 extending through the collar 14. The guide post 20 is mounted with its inner edge 24 flush with the inner edge of guide 13 so that the stacked articles 19 can pass through hole 18 in the collar 14 without obstruction. A screw 21, which holds the guide post 20 in place, is secured to the collar 14.

As FIG. 2 shows, the base plate 17 has holes 31 adapted to receive the lower ends of the guides 13. The holes 31 are spaced to hold guides 13 parallel. This enables the carrier assembly 12 to move freely on the guides. The lower ends of guides 13 are threaded and anchored to base plate 17 by nuts 23.

Referring to FIGS. 3 and 4, the carrier assembly 12 is suspended on tapes 26 which are anchored to the collar 14. Clearly, other flexible tension members such as wire cables may be used to replace tapes 26. The anchors consist of split bolt assemblies 27, which are screwed into collar 14, and locking nuts 28. The tapes 26 extend through the split bolt assemblies 27 and are held in place by locking nuts 28 which are mounted on upper tapered portions 29 of the split bolt assemblies 27. When the selfleveling lifter 10 is first assembled, the tapes 26 are adjusted so that a platform 30 mounted on the carrier assembly 12 is level. Subsequent adjustments can be made by loosening the nuts 28 and readjusting the tapes 26.

Referring to FIG. 5, the carrier assembly 12 is shown in greater detail. The carrier assembly consists of a frame 32 having the platform 30 welded to its top and a shaft 33 depending from its top. A tape reel assembly is mounted on shaft 33.

The tape reel assembly includes an inner axle sleeve 40, an upper spiral spring 41, an upper reel 42, an outer axle sleeve 43, a lower spiral spring 44, and a lower reel 45. In assembling the tape reel assembly, upper bearings 46 and the upper reel 42 are placed on the shaft 33 against a spacer 47. The inner axle sleeve 40 is then placed on the shaft 33 and the upper spiral spring 41 is installed between the inner axle sleeve 40 and the upper reel 42. Next, the outer axle sleeve 43 is placed over the inner axle sleeve 40 so a groove 48 in the outer axle sleeve 43 is aligned with a groove 49 in the inner axle sleeve 40. A bent end 52 of the upper spiral spring 41 fits into the aligned grooves 48 and 49 (see FIG. 7).

The lower spiral spring 44 is attached to lower reel 45 in a manner that, when assembled, it will wind about the shaft 33 in a direction opposite to upper spiral spring 41. The lower reel 45, the lower spral spring 44, and the lower bearing 50 are placed on the shaft 33. The lower reel 45 is rotated until a bent end 53 of the lower spiral spring 44 mates with the aligned grooves 48 and 29. A nut assembly 54 is mounted on the shaft 33 beneath the lower bearing 50.

When the upper reel 42 and the lower reel 45 are rotated in opposite directions, the inner and outer sleeves 40 and 43 will turn until the upper and lower spiral springs 41 and 44 are locked between grooves 48 and 49. Once the springs 41 and 44 are locked in place, the inner and outer sleeves 40 and 43 coact as a single freely rotating axle which acts on both the upper and lower spiral springs 41 and 44.

Three brackets 56 having vertical slots (see FIGS. and 6) depend from the top of the frame 32 and are radially spaced from the peripheries of the reels 42 and 45. A bolt 58 which mounts a roller 57 is positioned in the vertical slot of each bracket 56. Each of the rollers 57 extends between the upper reel 42 and the lower reel 45.

The rollers 57 maintain a predetermined vertical spacing between the reels 42 and 45.

Referring to FIGS. 5, 6 and 9, the upper and lower spiral springs 41 and 44 are each attached to an arm 59 with a screw 60. Each of the spiral springs 41 and 44 has several holes 61 adjacent one end adapted to receive the screw 60. The effective length and so the spring rate of each of the springs 41 and 44 is changed by using different ones of the holes 61 to attach the spring to the arm 59. The arms 59 extend through are shaped slots 62 in each of the reels 42 and 45 and each arm 59 is held by a nut 63.

The initial spring tension is set and subsequent adjustments are made by loosening one of the nuts 63 and sliding the arm 59 in the slot 62. Two spacer rollers 64 (see FIG. 9) mounted on each of the reels 42 and 45 keep the spiral springs 41 and 44 from interfering with the adjustment of the arms 59 and keep the springs from twisting to one side as they are wound up.

Each of the reels 42 and 45 is provided with a peripheral groove 65 (see FIG. 5) adapted to receive two of the tapes 26. The two tapes 26 are bolted to the inside of each reel by bolt and nut 66 which is mounted flush with the outer edge of the reel (see FIG. 8). The tapes 26 are wrapped around the nut and threaded through a slot 67 in the reel and over the head of the bolt. This prevents the bolt and nut 66 from loosening. The two tapes 26 on each reel 42 and 45 are wound on each of the reels in the same direction that the spiral spring for that reel is wound about shaft 33.

Referring to FIGS. 5, 6 and 9, the two tapes 26 on the upper reel 42 extend to diagonal corners of the carrier frame 32 and over upper rollers 67 which are bolted to the frame 32. The two tapes 26 on the lower reel 45 extend to the other two diagonal corners of the carrier frame 32 and over lower rollers 68 which are also bolted to the frame 32. The tapes 26 then extend upwardly substantially parallel to the guides 13 and the ends are anchored in the split bolt assembly 27 in collar 14, as described above.

It is to be noted that the platform will remain level as the carrier assembly moves up and down on guides 13. If a downward force is applied to one edge of platform 30, the tape 26 extending over the roller 67 or 68 nearest the applied force will unwind along with the tape over the furthest rollers 67 or 68. The downward force will also result in an unwinding of the other two tapes as the first two begin to unwind. As a result, each of the four tapes will unwind an equal amount and the platform will remain level.

The amount each tape will unwind for any given force is determined by the spring constant. Therefore, changing the effective length of the two spiral springs by changing the holes 61 from which they are connected to brackets 59 will change the amount the platform will move when the number of stacked articles is changed. The number of articles that can be stacked on the platform before it will move from its up position is adjusted by moving bracket 59 in slot 62 to set the initial spring force.

As the load of the stacked articles moves the platform 30 downwardly, the movement is opposed by upward forces generated 'by the spiral springs 41 and 44. The spring forces are transmitted to the tapes 26. The springs 41 and 44 are designed to produce forces which counterbalance the downward forces resulting from the addition of stacked articles onto the platform 30. The spring forces are such that the platform 30 is returned to a static condition when the uppermost stacked articles is at the predetermined vertical elevation. It is noted that because the inner and outer sleeves 40 and 43 rotate together on the depending shaft 33, the total forces on each pair of tapes 26 is essentially equal.

FIG. 10 shows a second preferred embodiment of the self-leveling lifter. In this embodiment a sleeve 70 is fastened with bolts 71 to upper reel 42 such that the sleeve and the upper reel can turn on shaft 33. As an alternative, the sleeve 70 could be welded to upper reel 42 or it could be cast as a part of upper reel 42. A single spiral spring 69 is connected between the sleeve 70 and an adjusting arm 72, which is locked in the arc shaped slot 62 in lower reel 45 with a nut 73. In this arrangement, the single spiral spring 69 replaces upper spiral spring 41, lower spiral spring 44, and the freely rotating axle formed by the inner axle sleeve 40 and the outer axle sleeve 43.

The spiral spring 69 can be attached to sleeve 70 with a screw, by welding, by inserting a tab bent in the end of the spiral spring into a slot cut into the sleeve, or by other obvious methods. A screw 74 is used to attach the outer end of the spiral spring 69 to the adjusting arm 72. Changing the hole 75 in the spiral spring 69 through which the screw 74 is inserted changes the effective length of the spring and therefore changes the spring rate. Two spacer rollers 76- (only one shown) are mounted to keep the single spiral spring 69 from twisting to one side as it is wound up.

The operation of the single spiral spring embodiment of the invention is similar to that of the embodiment using two spiral springs. As articles 19 are stacked on platform 30, the carrier assembly 12 descends on guides 13 and the pairs of tapes 26 unwind from the upper and lower reels 42 and 45. As the tapes unwind, the upper and lower reels 42 and 45 turn on shaft 33 in opposite directions, causing the single spiral spring 69 to wind up. It is noted that the total forces on each pair of tapes 26 is essentially equal because the upper reel 42 and the lower reel 45 are free to rotate on shaft 33 and the spiral spring 64 is attached between them.

Although the drawings show four guides, four tapes, two tape reels, and a circular platform, it is obvious that these may be changed to fit the requirements of the items to be stored. For example, for circular dishes, 21 single reel having three tapes wound on it can be used. Similarly, the platform and collar may be made square to receive trays, or the like.

It will be appreciated that other arrangements, modifications and changes may be made without depant-ing from the scope of the appended claims.

What I claim is:

1. A self-leveling lifter for storing and dispensing stacked articles, wherein the uppermost one of the stacked articles rests at a predetermined vertical elevation, said lifter comprising, in combination, a frame, a platform mounted for vertical movement in said frame, a shaft depending from said platform, a reel rotatably mounted in coaxial relationship on said shaft, a spiral spring mounted on said shaft, said spring having one end operatively connected to said shaft and its other end operatively connected to said reel, and a plurality of elongate flexible members wound around said reel, each of said members having one end connected to the reel and the other end operatively connected to said frame, whereby when stacked articles are placed on such platform moving such platform downwardly, the force of the spiral spring transmitted through such members resists the downward movement of the platform bringing the platform to rest with the uppermost stacked article being located at the predetermined elevation.

2. A self-leveling lifter according to claim 1, including guide means for guiding the vertical movement of said platform along a predetermined path.

3. A self-leveling lifter according to claim 2, including adjusting means for adjusting the tension of said spiral spring.

4. A self-leveling lifter according to claim 1, including means for changing the rate of said spiral spring by changing the effective length of said spring.

5. A self-leveling lifter for storing and dispensing stacked articles, wherein the uppermost one of the stacked articles rests at a predetermined vertical elevation, said lifter comprising, in combination, a frame, a platform mounted for vertical movement in said frame, a shaft depending from said platform, first and second reels rotatably mounted in coaxial relationship on said shaft, a spiral spring mounted on said shaft, said spiral spring having one end operatively connected to said first reel and its other end operatively connected to said second reel, at least one elongate flexible member wound about said first reel, said member being attached at one end to said first reel and at its other end to said frame, and at least one second elongate flexible member wound about said second reel, said second member being attached at one end to said second reel and at its other end to said frame, whereby when stacked articles are placed on such platform moving such platform downwardly, the. force of the spiral spring transmitted through said elongate flexible members resists the downward movement of the platform bringing the platform to rest with the uppermost stacked article being located at the predetermined elevation.

6. A self-leveling lifter according to claim 5, including means for changing the rate of said spiral spring by changin g the effective length of said spring.

7. A self-leveling lifter according to claim 6, including adjusting means for adjusting the tension of said spiral spring.

8. A self-leveling lifter for storing and dispensing stacked articles, wherein the uppermost one of the stacked articles rests at a predetermined vertical elevation, said lifter comprising, in combination, a frame, a platform mounted for vertical movement in said frame, a freely rotating axle operatively mounted on said platform, first and second reels rotatably mounted in coaxial relationship with said axle, first and second spiral springs mounted on said axle, said first spring having one end attached to said axle and having its other end operatively connected to said first reel, said second spring having one end attached to said axle and having its other end operatively connected to said second reel, said second spring being wound around said axle in a direction opposite from said first spring, at least one elongate flexible member wound about said first reel, said member being attached at one end to said first reel and at its other end to said frame, and at least one second elongate flexible member wound about said second reel, said second member being attached at one end to said second reel and at its other end to said frame, whereby when stacked articles are placed on such platform moving such platform downwardly, the force of the spiral springs transmitted through their respective elongate flexible members resists the downward movement of the platform bringing the platform to rest with the uppermost stacked article being located at the predetermined elevation.

9. A self-leveling lifter according to claim 8, including guide means for guiding the vertical movement of said platform along a predetermined vertical path.

10. A self-leveling lifter, according to claim 9, including adjusting means for adjusting the tension of said first and second springs.

11. A self-leveling lifter, according to claim 10, including means for changing the effective length of said first and second springs.

12. A self-leveling lifter for storing and dispensing stacked articles, such that the uppermost one of the stacked articles rests at a predetermined vertical elevation, said lifter comprising, in combination, a support housing having an article receiving opening defined in its upper surface, a platform mounted Within said support housing for vertiral movement along a predetermined path, a plurality of vertical guide rods mounted in said support housing adjacent said platform for guiding said platform along such predetermined path, a vertical shaft depending from said platform, a freely rotating axle mounted on said shaft, first and second reels, having tape receiving grooves in their peripheries, rotatably mounted on said shaft, first and second spiral springs Wound around said axle in opposed directions, said first spiral spring having one end connected to said axle and its other end operatively connected to said first reel, said second spiral spring having one end connected to said axle and its other end operatively connected to said second reel, means for adjusting the tension of said first and second spiral springs, a first pair of tapes engaged in such tape receiving groove of said first reel, said first pair of tapes having one end attached to said first reel and their other ends attached adjacent diagonal upper corners of said support housing, and a second pair of tapes engaged in such tape receiving groove of said second reel, said second pair of 8 tapes having one end attached to said second reel and their'other ends attached adjacent the remaining diagonal upper corners of said support housing.

References Cited UNITED STATES PATENTS 3,302,827 2/1967 Maslow 312-71 3,342,536 9/1967 Cohen 312-71 3,357,760 12/1967 Shelley et al 3127l BOBBY R. GAY, Primary Examiner.

J. L. KOHNEN, Assistant Examiner, 

